;+
;FUNCTION: v_4d(dat,ENERGY=en,ERANGE=er,EBINS=ebins,ANGLE=an,ARANGE=ar,BINS=bins,MASS=ms,m_int=mi,q=q,mincnt=mincnt)
;INPUT:
; dat: structure, 4d data structure filled by themis routines mvn_sta_c6.pro, mvn_sta_d0.pro, etc.
;KEYWORDS
; ENERGY: fltarr(2), optional, min,max energy range for integration
; ERANGE: fltarr(2), optional, min,max energy bin numbers for integration
; EBINS: bytarr(na), optional, energy bins array for integration
; 0,1=exclude,include,
; na = dat.nenergy
; ANGLE: fltarr(2,2), optional, angle range for integration
; theta min,max (0,0),(1,0) -90<theta<90
; phi min,max (0,1),(1,1) 0<phi<360
; ARANGE: fltarr(2), optional, min,max angle bin numbers for integration
; BINS: bytarr(nb), optional, angle bins array for integration
; 0,1=exclude,include,
; nb = dat.ntheta
; BINS: bytarr(na,nb), optional, energy/angle bins array for integration
; 0,1=exclude,include
;PURPOSE:
; Returns the velocity, [Vx,Vy,Vz], km/s for each mass bin
;NOTES:
; Function normally called by "get_4dt" to
; generate time series data for "tplot.pro".
;
;CREATED BY:
; J.McFadden 14-02-26
;LAST MODIFICATION:
;-
function v_4d,dat2,ENERGY=en,ERANGE=er,EBINS=ebins,ANGLE=an,ARANGE=ar,BINS=bins,MASS=ms,m_int=mi,q=q,mincnt=mincnt
vel = [0.,0.,0.]
if dat2.valid eq 0 then begin
print,'Invalid Data'
return, vel
endif
if dat2.nbins eq 1 then return,vb_4d(dat2,ENERGY=en,ERANGE=er,EBINS=ebins,ANGLE=an,ARANGE=ar,BINS=bins,MASS=ms,m_int=mi,q=q,mincnt=mincnt)
flux = j_4d(dat2,ENERGY=en,ERANGE=er,EBINS=ebins,ANGLE=an,ARANGE=ar,BINS=bins,MASS=ms,m_int=mi,q=q,mincnt=mincnt)
density = n_4d(dat2,ENERGY=en,ERANGE=er,EBINS=ebins,ANGLE=an,ARANGE=ar,BINS=bins,MASS=ms,m_int=mi,q=q,mincnt=mincnt)
if keyword_set(ms) then begin
return, 1.e-5*flux/(density+1.e-10)
endif else begin
return, 1.e-5*reform([flux[0,*]/(density+1.e-10),flux[1,*]/(density+1.e-10),flux[2,*]/(density+1.e-10)],3,n_elements(density))
endelse
end